1. Field of the Invention
This invention relates to electro-optical components, and, more particularly, to a vertical electro-optical component and a method of fabricating the same.
2. Description of Related Art
In semiconductor-based photodetectors, photons excite movable carriers, to generate currents. A general photodetector comprises transistors. A transistor is a three-terminal component, may amplify photoresponse signals, and has a significant regulation and photoresponsivity.
In order to improve the operational characteristics of the semiconductor itself, several prior arts are brought to the market.
M. C. Hamilton et al. disclosed in “IEEE Trans. Electron Devices, vol. 51, no. 6, pp. 877-885,” published on June, 2004, a general three-terminal horizontal photo semiconductor. Although having a higher light sensitivity, the horizontal photo semiconductor has a lower overall response speed and a higher operational voltage (e.g., greater than 10 volts), as compared to a general photo diode, because its response involves the generation of defect states and the trap and relaxation of carriers and it cannot discompose excitons effectively.
P. Peumans et al. disclosed in “Appl. Phys. Lett. 76, 3855,” published on 2000, a general photo diode. Though having a higher response speed, the photo diode has no advantage in circuit applications, since it is a two-terminal component.
K. Kudo et al. disclosed in “Thin Solid Films 438, 330,” published on 2003, and K. Kudo disclosed in “Current Applied Physics 5, 337,” published on 2005, a vertical light-emitting transistor, in which a gate is fabricated in a light-emitting layer. However, the steps of fabricating the mesh gate are complicated, and it is difficult to control the thickness of the gate layer. Too thick the gate layer may prevent currents from flowing from a source to a drain, while the gate cannot control the currents effectively if the gate layer is too thin. Accordingly, it is difficult to control the overall fabrication process, and the component is unstable.
U.S. Pat. No. 6,967,436B2 disclosed a display with a third electrode inserted therein. Since the third electrode is far from a light-emitting area, the light-emitting area thus has a potential that is difficult to be controlled, and performs a poor switching characteristic.
U.S. Pat. Nos. 7,633,084B2 and 7,126,153B2 disclosed embedding base metal into a semiconductor. Since no insulating layer is used that may prohibit the leakage currents between a base and an emitter or between the base and a collector, the transistor does not have a significant switching characteristic, and may suffer from a great power loss.
Therefore, in view of the problems of the prior art, to effectively and conveniently improve the component characteristics of a vertical electro-optical component, especially in increasing the reaction speed and reducing the operational voltage, in order to improve the efficiency of an electro-optical component, is becoming one of the most popular issues in the art.